Objective: The aim of this project is to develop a novel source of adult stem cells as an alternative to embryonic-derived stem cells/tissue for neural grafting in Parkinson's disease (PD). Bone marrow-derived hematopoietic stem cells and brain-derived adult ependymal stem cells will be investigated with respect to their potential to differentiate into dopaminergic (DA-ergic) neurons in vitro: In a final phase, the cells will be grafted into PD animal models. The work program includes (phase 1) isolation and purification of both cell types by using specific markers and magnetic sorting or FACS. In phase 2, cells will be propagated in vitro and characterized; respective mitogenes screened and protocols optimized. Phase 3 involves the identification of factors promoting neuronal/DA-ergic differentiation for the respective cell types and optimization of differentiation protocols in vitro. Cells will be characterized morphologically by immunocytochemistry and functionally by measuring K+-stimulated DA release in vitro. Subsequently, to verify a possible clinical application of the investigated cell types for neural grafting, undifferentiated as well as differentiated cells will be transplanted intracerebrally in rat/mouse models of PD in phase 4. Grafted cells will be assessed morphologically by immunohistochemistry, their ability to form synaptic contacts with the host brain by staining for synaptic vesicle proteins (such as synaptophysin) in combination with confocal and electron microscopy. Functionality of grafted cells will be tested by rotational behavior pre- and post transplantation. The project is aimed at further understanding of neural stem cell biology and more importantly, to use a highly goal-derived approach to develop a translation protocol for adult-derived stem cells that can be readily applied in future clinical trials in PD.